Garden Know-How: Extend Your Growing Season

Learning a few season extension techniques can help you start your garden up to six weeks earlier and enjoy fresh food sooner.

By Barbara Pleasant

| February/March 2007

Plastic-covered tunnels make perfect mini-greenhouses for early spring planting.

Phtoto courtesy ROBIN WIMBISCUS

As late winter days lengthen, resourceful gardeners scurry to collect cloches, erect plastic-covered tunnels and put together a workable cold frame. Using season-stretching devices such as these can add four to six weeks to the front end of your growing season (and many of them will be handy again in the fall).

You can make an amazing array of season-stretching garden gear from found or recycled materials, and you won’t have to rely on electric grow lights to get delectable spring greens in time for Easter or have the first ripe tomatoes on your block. Creating season-extending equipment is fun because you’re working with free solar energy. The trick is to come up with simple structures that can withstand strong winds, shed rain and snow, and absorb and store solar warmth for the plants you’re protecting.

Physical shelter from blustery weather will help any plant, but cool-natured plants such as lettuce, spinach and cabbage-family crops don’t need as much heat as tender tomatoes or peppers — especially at night. Simple plastic cloches or plastic-covered cold frames raise nighttime temperatures 4 to 5 degrees, but you can double that number by throwing on an insulating blanket in the evening. Or triple the protection by adding black water bottles, which release stored daytime warmth after the sun goes down.

Try Creative Cloches

Low, transparent individual plant protectors, called cloches, are the season-stretchers of choice for plants spaced more than 8 inches apart, such as tomatoes and peppers. Most gardeners keep a stash of cloches made from translucent plastic milk jugs or clear plastic bottles. I pick up roomy plastic juice jugs with handles at my local recycling center.

Water-filled containers painted flat black absorb solar warmth during the day and release it at night, so they are worthwhile additions to your season-stretching toolbox.Phtoto courtesy ROBIN WIMBISCUS

Straw or hay bales can easily be combined with an old window to make a nifty cold frame.Phtoto courtesy ROBIN WIMBISCUS

Before cutting off the bottom of any jug, I make a vee-shaped slit in the top of the handle. Later, I can shove a long, slender stick through the slit and down into the soil to help hold the cloche steady in the wind.

Even when anchored by mulch, strong winds may blow away many cloches — except for heavy ones such as the Wall O’ Waters, which weigh about 25 pounds when filled. A circle of water-filled plastic drink bottles duct-taped together is heavy enough to stay put and hold down the edges of a sheet of plastic tucked around the cloche for extra frost protection. Countless other items make great emergency cloches for freaky cold spells, including plastic cake covers, upturned flowerpots, cardboard boxes, buckets, baskets, and old lampshades or light fixtures.

Make Terrific Tunnels

Plastic-covered tunnels make perfect mini-greenhouses for early spring planting. You also can use one to harden off seedlings started indoors. Low tunnels stand firmer in wind than high ones, and tunnels that must hold up under heavy snow loads benefit from sturdy support. Supporting a tunnel is a great job for fence wire or concrete reinforcing wire. Or, you can go with simple hoops if you keep your tunnels low and tight. I make hoops from slender green saplings cut from the woods, or you can use stiff wire or small diameter plastic pipe. Got raised beds? Attach matching pairs of pipe brackets to the outside of the beds’ sides, and you have instant sleeves for support hoops.

My first tries with tunnels led to long tramps through the woods to retrieve windblown sheets of plastic, but not anymore. After trying edge-weights from bricks to warped landscaping timbers, I’ve settled on angular (rather than round) pieces of firewood, wrapped over twice with the plastic. When cutting plastic for a tunnel, allow a generous 2-foot overhang on both sides so you’ll have enough to wrap around whatever weights you decide to use to secure your tunnel’s edges.

Extra warmth in the daytime is often a plus, too, though it can become a problem if the enclosure lacks adequate ventilation. You can ventilate tunnels by using slitted plastic, which is a bit pricey and not widely available in small quantities, or by simply opening the ends of the tunnel and using clothespins or spring-clips to hold the bunched plastic open. Downward-facing vee-shaped vents cut in the sides of a tunnel and reinforced with duct tape improve ventilation, too. For extra insulation against cold, simply cover your tunnels with old blankets or bedspreads on frigid nights. During late-season winter storms, it won’t hurt the plants inside to leave the blankets on for up to four days.

-Advertisement-

Make Super-Easy Mini-Greenhouses

You can extend your growing season in spring and fall with these low-cost, easy-to-make plant protectors. Welded wire fencing with 2-by-4-inch openings works great for low tunnels that let you plant crops several weeks earlier than usual. Strips of 5-foot tall fencing can be bent to make a cover with 1-foot high sides that will protect a 30- to 36-inch wide bed of any length. Bend the wire to the shape you want, then lay it top-down onto a sheet of clear plastic. Fold the plastic up and over the long edges of the wire, then tape the edges down inside the tunnel with clear packaging tape. Leave a couple of feet of plastic at each end so you can fold it in to close the tunnel when the weather turns really cold. These lightweight tunnels are easy to lift off the bed so you can weed and water, and easy to stack when not in use. You can cover the wire frames with fabric row cover or bird netting and use them to protect crops from insect pests, birds or deer. If your site is windy, use “staples” made from wire coat hangers to stake down the tunnels.

For taller tunnels to protect tomatoes or other crops in the fall, concrete reinforcing wire will work better than the lighter weight welded-wire fencing. If you want to use the plastic for both spring and fall protection, use lengths of iron re-bar to hold down the plastic edges, rather than folding under and taping. This will allow you to easily remove the plastic during the hot months when it is not needed.

Create Classic Cold Frames

A stationary cold frame is invaluable for hardening off tender seedlings, or you can make a movable one. (“Cold frame” refers to any unheated boxed-in growing area with a clear glass or plastic top to admit light and trap solar heat.) Opt for a well-built permanent cold frame if you have a great site, such as a south-facing slope for an earth-bermed version. Otherwise, it’s handy to be able to pop a portable frame over a bed of direct-sown crops for a week or two, and then move it to a place where it can serve as a halfway house for seedlings started indoors.

A wood frame covered with plastic sheeting makes a decent cold frame, or you can use hay bales for the walls. An old window still in its frame, with opening and closing hardware intact, makes a great top, and I’m happy as pie with the $5 shower door I found at my local Habitat for Humanity thrift store. Found items like these often come in strange sizes, so it’s best to get a top before you make a frame. You might need to get creative with hinges, too, especially if the window or door has a metal frame. Pieces of old bicycle inner tube stapled or screwed into place make good, inexpensive hinges. The wind won’t rip off your cold frame’s top if it’s secured to the base (when closed) or to sturdy wood stakes (when open) with screen-door hooks and eyes.

Other good season-stretching strategies include wrapping the outside of a tomato cage with clear plastic, or stapling bubble wrap over the top of a cardboard box with its top flaps folded in for added stability, and its bottom flaps folded out and held in place with bricks or stones. Use what you have! Until it got too nasty to keep, I used an old mattress pad for quickie overnight plant protection, and a friend is determined to find the best way to transform used Styrofoam take-out boxes into cloches. When it comes to inviting spring into your garden a few weeks early, a little imagination can go a long way.

-Advertisement-

Solar-charged Hot Water Bottles

Water-filled containers painted flat black absorb solar warmth during the day and release it at night, so they are worthwhile additions to your season-stretching toolbox. The squared sides of half-gallon milk jugs make them easy to stack into the back wall of a cold frame, or you can include a black water-filled barrel in your cold frame’s design.

In thousands of cold-climate gardens, bed warmers made from soft drink bottles are considered basic gardening equipment. Or the drink bottles can be duct-taped into cylinders, like the one shown at right, to give tomatoes, peppers and other tender seedlings an earlier start.

Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on Google+.

Share your thoughts.

theresa

4/16/2015 11:37:32 AM

My husband and i are trying to figure out what to grow in our new greenhouse during the very hot august heat. I've heard okra loves the heat? We constructed a nice greenhouse from http://cookingfirewood.com and we are just trying to plan out out summer season. My husband is leaving the research up to me, lol ! Anyway, I LOVE your magazine and site.
Thank you!
Theresa Filman

ronald ellis

11/8/2010 11:40:38 AM

Here in south-central Alabama we worry less about frost and more about insects, which because of the warm weather are with us most of the year.
In the fall, cabbage worms and their mothers (yellow butterflies)are constantly on the move. So, my low greenhouse is covered with super lightweight row covers to prevent the butterfly from laying her eggs on my collards and cabbages.
For decades now I've built my low greenhouses of half-inch, schedule 40 PVC pipe. I drive steel rebar in the ground to hold the pipe hoops in place. Once row cover fabric is on I use bungee cords to hold it down, and it works even when we have hurricane force winds.
If anyone wants a step-by-step pictorial tutorial, go to my blog:
http://blog.springmeadoworganics.com/
Mother Earth News was a revolution when it was first launched, and continues to be such today.
Thanks for all that you do.

l a graham

8/30/2010 2:06:01 PM

I had some old vinyl portable storage closets that I converted into mini-greenhouses. They were ideal because the "door" zips open from across the top and down, so I could unzip it a short ways and the heat would escape through the open part of the door. The top is black fabric, so in dry weather it absorbs the heat well; when wet weather is due, during cold weather I cover the top with weighed-down sheet plastic and in warm weather just leave the fabric uncovered and let the rainwater seep through to the plants. This is working for me much better than the mini-greenhouses that I bought at a clearance center; they had no vents and the plants were frying. I removed the covers from those frames, which included wire shelves, and set the framework and shelves inside the closets.

lillian maresch_1

1/20/2010 3:02:29 AM

Please forgive me if this message is a duplicate of one just logged in - don't know if the first one went through.
I'm trying to locate Bob Kornegay in Rutherfordton, NC, where I'm told he is currently living and working.
An artist friend of Bob's who thinks very highly of him strongly recommended that we contact Bob ASAP to help us set up thermal heating in the off the small grid home we are constructing in NC. However, we cannot find a phone # or any contact info for him.
Thank you for any help you may be able to offer us in contacting Bob as soon as possible!
All the best, Lillian 864-895-1857

lillian maresch_1

1/20/2010 2:58:29 AM

I am trying to get a contact phone # or email address for Bob Kronegay in Rutherfordton, NC. Might someone at Mother Earth News be able to help me with this?
An artist friend of Bob's strongly recommended that we contact Bob ASAP to set up thermal heaters but we are unable to locate any contact info for Bob.
Many thanks for any help you can offer us!
Blessings and gratitude, Lillian

norma _2

1/16/2010 9:22:36 PM

Recycled styrofoam coolers or minnow buckets are wonderful protection from even the hardest freeze in early spring. We had a particularly bad hard freeze in late-April a couple of years ago (-2 degrees) and we covered all of our plants. The only ones that survived it were the ones we covered with old minnow buckets.

Money-Saving Tips in Every Issue!

At MOTHER EARTH NEWS, we are dedicated to conserving our planet's natural resources while helping you conserve your financial resources. You'll find tips for slashing heating bills, growing fresh, natural produce at home, and more. That's why we want you to save money and trees by subscribing through our earth-friendly automatic renewal savings plan. By paying with a credit card, you save an additional $5 and get 6 issues of MOTHER EARTH NEWS for only $12.00 (USA only).